噴灑頭式MOCVD反應器之熱流場與化學場數值模擬分析

Abstract

以CFD方法來模擬分析MOCVD反應腔體之薄膜沉積已日漸重要，對於實驗亦或是生產線，皆希望能在操作開始前預先了解晶圓片之反應特性、沉積缺陷區、優點與缺點，因此本研究藉由軟體ANSYS Fluent 14.5來模擬分析噴灑頭式MOCVD反應器之熱流場與化學場，觀察GaAs沉積速率與三種不同承載盤轉速間的關係，並且利用反應氣體濃度分布找出各反應方程式之反應區間及反應溫度。本研究從部分結果中得知入口氣體之三、五族流量比例對於沉積速率及品質影響甚大，因此亦對入口氣體之三、五族流量比例做進一步的模擬分析。 結果顯示，一甲基鎵濃度分布因受流場影響，導致三種不同轉速中500rpm之GaAs沉積速率最高，均勻度亦最大。隨著三甲基鎵流量增加，GaAs沉積速率及均勻度皆上升，且沉積速率上升之比例與流量增加的比例幾乎一致。 綜合上述，利用CFD方法可以準確模擬出薄膜之沉積速率及品質，且能利用暫態分析的優勢，觀察腔體熱流場及化學場，找出影響沉積速率之因素。

It’s being increasingly important to use CFD technology to analyze thin film deposition of MOCVD reactor. For experiments and industry, we hope to find out characteristics of reactions, defect of deposition, advantage and shortcoming on wafer before operate. In this study, we analyze numerically chemical reactions and thermal fluid dynamics in MOCVD reactor by ANSYS Fluent 14.5. We not only observe the relationship between GaAs growth rate and three different rotating speed of susceptor but also find out the reaction interval and reaction temperature. From the preliminary results, we obtain the GaAs growth rate and uniformity are also affected by flow rate of the inlet gas (Ⅲ/Ⅴ ratio). So we simulate numerically other case about the relationship between GaAs growth rate and different flow rate of inlet gas. From the results, there is the fastest GaAs growth rate and highest uniformity in 500rpm rotating speed because of the distribution of MMGa molar concentration is affected by flow field. With the increase of TMGa flow rate, GaAs growth rate and uniformity are both increased. Furthermore, the increased multiple of GaAs growth rate is almost unanimous with the increased multiple of TMGa flow rate. Therefore, we can simulate accurately growth rate and uniformity by CFD technology. Besides we can also analyze flow field and distribution of concentration in the chamber with transient state, and find out the key factors that affect growth rate.